identd: Fix "brew audit" offenses

identd: Fix "brew audit" offenses

C:  1:  9: Prefer double-quoted strings unless you need single quotes
           to avoid extra backslashes for escaping.
C:  4:  7: Prefer double-quoted strings unless you need single quotes
           to avoid extra backslashes for escaping.
C:  5: 11: Prefer double-quoted strings unless you need single quotes
           to avoid extra backslashes for escaping.
C:  6: 12: Prefer double-quoted strings unless you need single quotes
           to avoid extra backslashes for escaping.
C: 17:  7: Use %r around regular expression.
C: 19: 18: Prefer double-quoted strings unless you need single quotes
           to avoid extra backslashes for escaping.
C: 20: 18: Prefer double-quoted strings unless you need single quotes
           to avoid extra backslashes for escaping.

Signed-off-by: Alexander Barton <alex@barton.de>